Method of machining a thermosetting laminate

ABSTRACT

Method of machining a thermosetting laminate (13) by means of an apparatus comprising at least one high-frequency or ultrasonic oscillation generator (1) and at least one dimension changing or adjusting unit (4) having at least one piezoelectric crystal (8) performing a linear vibration when charged with an alternating current. The linear vibration is propagated through at least one mechanical or electronic amplitude transforming unit (5), whereby generated high-frequency or ultra-sound amplitude is transformed into a linear vibration. The linear vibration is during machining propagated via at least one tiller or tool holder (7), being connected to the amplitude changing unit (5), to at least one tool (2) attached to the tiller or tool holder (7) and consisting of a least one diamond (3), whereby at least said tool (2) performs a linear vibrating movement (16) and whereby said tool (2) executes said machining.

The present invention refers to a method of machining a thermosettinglaminate, whereby said machining is a planing operation, such as an edgechamfering, an edge trimming, a jagging, a guttering, a grooving or thelike. The planing is preferably an edge chamfering. The machining isperformed by means of a high-frequency or ultrasonic planing machinehaving a planing tool consisting of at least one diamond or othermaterial having a hardness according to Vickers of at least 1400-1600kp/mm².

Thermosetting laminates are among other applications used as floor,wall, ceiling or furniture surfacing. Thermosetting laminates used insaid application are normally produced in form of or cut into boards,plates, sheets, panels, bars and the like, whereby the laminateoptionally is bonded to a carrier consisting of for instance fibreboard, particle board, wood, plywood and similar materials. The boards,plates, sheets, etc. are then arranged side-by-side to a coveringdecorative and/or protective surface. The boards, plates, sheets, etc.are often or even normally machined to produce grooves, tenons, smoothedges, chamfers, jags, channels and the like. The edges of boards,plates, sheets, etc. are normally machined or tooled, using for instancea chamfering plane, to obtain smooth edges and smooth level crossingbetween boards, plates, sheets, etc. joint side-by-side. A smooth andplane level crossing increases substantially the abrasion resistanceover the joint and decreases substantially damages and injuries to forinstance an obtained surfacing and to objects, materials and personscoming into contact therewith.

Edge chamfering is normally carried out using a planing machine providedwith a planing tool made for instance in a hard metal or metal alloy,such as steel or titanium. This kind of planing is less or not at allsuitable for machining of materials such as thermosetting laminates. Thehardness of the thermosetting laminates creates as well as emphasise anumber of problems and negative effects, which can be summarised:

rapid deterioration of the planing tool and thus tooling quality andaccuracy as well as increased costs and decreased product quality,

heavy heat release during tooling with pendant discoloration of thetooling zone,

reduced or no possibility, due to the rapid tool deterioration and theheavy heat release, to increase the tooling speed or rate,

large variations in the dimensions of the machined area including largevariations in the size and angle of for instance a chamfer.

Chamfering of thermosetting laminates is per se a specific problem in.that the presently and normally machined chamfer of approximately0.3-0.5 mm or even larger, with a deviation of ±0.1 mm or more, does notcomply with a long standing customer demand for chamfers ofapproximately 0.1-0.2 mm or less. Accumulation of particles, dirt andother impurities, giving rise to for instance abnormal abrasion over thechamfer and hygienic problems, is one specific reason why reducedchamfer dimensions are required. The demand can neither be satisfied byconventional planing machines presently used nor by tools as disclosedabove. It is from many reasons very difficult or impossible to produce,using conventional planing, cutting or milling machines, a chamfer beingsmaller than said 0.3-0.5 mm, which even that is difficult to obtainmaintaining tooling quality and accuracy at high or at least acceptablelevels.

Thermosetting laminates are well-known products used as instance asfloor, wall, ceiling, furniture surfacing or as kitchen furnishings,whereby the laminate is decorative and/or protective. A thermosettinglaminate most often comprises a core consisting of for instance Kraftpaper impregnated with an epoxy resin or a phenol-formaldehyde resin, amonochromatic or patterned paper impregnated with amelamine-formaldehyde or urea-formaldehyde resin and optionally a socalled overlay of α-cellulose impregnated with a melamine-formaldehyderesin. A number of these various papers in form for sheets or webs arelaminated together under heat and pressure. Commonly used are alsolaminates bonded, such as glued, to a carrier consisting of for instancefibre board, particle board, wood, plywood and the like. The variouspaper sheets or webs, as disclosed above, can also be laminated and thusbonded directly to said carrier. Furthermore, the abrasion resistance ofa thermosetting laminate can, as for instance disclosed in the Europeanpatent no. 0 329 154 (corresponding to U.S. Pat. No. 4,940,503), beincreased by addition of hard particle, for instance aluminium oxide,when preparing for instance said overlay. An addition of hard particlesmakes discussed machining problems even more pronounced.

The present invention discloses a method of machining thermosettinglaminates and eliminates or substantially reduces discussed problems anddrawbacks. The machining is in preferred embodiments a planing operationcarried out on a thermosetting laminate, which laminate preferably isused as a floor, wall, ceiling or furniture surfacing or as a kitchenfurnishing, all in the form boards, plates, sheets, panels, bars and thelike. The planing is in preferred embodiments an edge trimming, ajagging, a guttering, a grooving and in the most preferred embodimentsan edge chamfering at an chamfer angle of 10-80° such as 30-60°resulting in a chamfer being less than 0.30 mm, preferably within therange of 0.05-0.20 mm. The planing is carried out by means of anapparatus comprising at least one high-frequency or ultrasonicoscillation generator and at least one dimension changing or adjustingunit having at least one piezoelectric crystal performing a linearvibration when charged with an alternating current. The linear vibrationis propagated through at least one mechanical or electronic amplitudetransforming unit, preferably comprising at least one mechanicalbooster, and the amplitude of generated high-frequency or ultra-sound,preferably having a frequency of 5-60 such as 10-40 or 15-25 kHz, istransformed into a linear vibration which during machining is propagatedvia at least one tiller or tool holder, such as a mandrel, connected tothe amplitude changing unit. The tiller or tool holder is provided withat least one planing tool consisting of at least one diamond and atleast said planing tool performs a linear horizontally and/or verticallyoriented vibrating movement, whereby said planing tool executes saidplaning. The diamond is suitably attached to the tiller or tool holder,which in preferred embodiments is made of steel or titanium, by vacuumsoldering. Normally and from a technical point of view preferably, saidtiller or tool holder and said planing tool both perform said vibratingmovement whereby only said planing tool is the machining member thereof.

The method of the present invention is primarily intended for machiningof thermosetting laminates, but can also be used for similar machiningof other materials being hard and/or difficult to machine, such asstone, concrete, ceramics and glassware.

Disclosed method and high frequency or ultrasonic apparatus and tool arecost saving in comparison to known rotating instruments, whereinmachining is carried when a number of tools, such as 8, 16, 24 or more,made of steel, titanium, diamonds and the like are placed in apre-determined order. Each tool carry, through the instrument rotation,out a pre-determined part of a machining sequence involving all in theinstrument included tools. The apparatus used according to the method ofthe present invention requires in preferred embodiments only one toolexecuting the entire machining, whereby reducing costs as well asfacilitating adjustment of the tool and thus increasing machiningaccuracy.

A thermosetting laminate, machined according to the method of thepresent invention, comprises at least one material, preferably acellulose, a fibre-glass or a textile material, in form of a web, asheet, threads or cut fibres. The material is impregnated with at leastone thermosetting resin which under heat and/or pressure is fully cured.Preferred thermosetting resin can suitably be exemplified by resins suchas polyester resins, epoxy resins, melamine-formaldehyde resins,urea-formaldehyde resins, phenol-formaldehyde resins as well ascombinations thereof and therewith.

Preferred embodiments of the thermosetting laminates, machined accordingto the invention, comprise at least one core consisting of at least oneKraft paper web or sheet impregnated with at least one thermosettingresin, preferably an epoxy resin or a phenol-formaldehyde resin and/orat least one patterned or monochromatic paper web or sheet impregnatedwith at least one thermosetting resin, such as a melamine-formaldehydeand/or urea-formaldehyde resin. The thermosetting laminates can alsosuitably comprise at least one so called overlay consisting of orcomprising at least one web or sheet of α-cellulose fibres impregnatedwith at least one thermosetting resin, preferably a urea-formaldehyderesin or a melamine-formaldehyde resin. Furthermore, said overlay and/orsaid patterned monochromatic paper sheets or webs can advantageously besurfaced with hard particles, such as aluminium oxide. Hard particlesare added before, during or after impregnation, but before curing of thethermosetting resin. The various webs or sheets are finally stacked uponeach other, in a pre-determined order and number, and are then laminatedtogether under heat and pressure. Each thermosetting resin used forimpregnation is individually partially or fully cured during saidlamination.

The thermosetting laminates disclosed above can of course as mostlaminates be bonded to a carrier, which preferably consists of wood,fibre board, particle board, plywood or the like. The by laminationobtained laminate is whereby glued or by other means attached to saidcarrier. The various webs and sheets can alternatively be directlylaminated, as above, under heat and pressure to the carrier. Thethermosetting laminate is in these embodiments the member subjected tosaid machining.

The present invention provides a method of improved machining, whereinthe improvements include:

machining of hard materials, such as thermosetting laminates, stone,concrete, ceramics and glassware, without rapid deterioration ofmachining tools,

improved tooling quality and accuracy with pendant decreased costs andincreased product quality,

no or substantially reduced heat release during machining and thus no orsubstantially reduced discoloration of the tooling zone,

possibility to increase the tooling speed or rate without rapid tooldeterioration and heavy heat release,

small dimension deviations of the machined area and possibility tomachine very small dimensions, such as chamfers being up to 60% smallerthan presently and normally machined ones.

These and other objects and the attendant advantages will be more fullyunderstood from the following detailed description, taken in conjunctionwith embodiment examples 1 an 2 and appended drawings, wherein likereference numerals have been applied like parts throughout the variousfigures.

Example 1: Edge chamfering at various target dimensions and variousmachining speeds.

Example 2: Abrasion over the chamfer at various chamfer dimensions.

FIG. 1: Shows schematically one embodiment of an apparatus comprising achamfering tool used to carry out an edge chamfering in accordance withthe method of the present invention.

FIG. 2: Shows in a cut-out the chamfering tool of FIG. 1 duringmachining of a thermosetting laminate bonded to a carrier.

The various parts of FIGS. 1 and 2 are not entirely according to scale,some part are for reason of clarity and simplicity enlarged or reduced.

While particular embodiments of the invention will be shown, it will beunderstood, of course, that the invention is not limited thereto sincemany modifications may be made, and it is, therefore, contemplated tocover by the appended claims any such modifications as fall within thetrue spirit and scope of the invention.

EXAMPLE 1

Boards consisting of a thermosetting laminate glued onto a carrier ofparticle board were edge chamfered at three different target dimensionsand three different machining speeds. An apparatus according to FIG. 1was used to carried out said chamfering. Two boards were at eachdimension and each speed chamfered and each chamfer were measured atfour different positions (C₁ -C₄). An average chamfer (C_(av)) and astandard deviation (σ) were from the four measurements calculated foreach board. The chamfering were carried at an chamfer angle of 45° withthe laminate pointing downwards. The boards were mechanically fed andkept at an invariable horizontal position. Used apparatus had amachining (feeding) speed of max. 50 m/minute.

Target dimensions and machining (feeding) speeds:

1. 0.07 mm-6.5 m/min.

2. 0.07 mm-21 m/min.

3. 0.10 mm-40 m/min.

4. 0.18 mm-6.5 m/min.

Obtained results are given in Tables 1-4 below.

                  TABLE 1                                                         ______________________________________                                        Target dimension: 0.07 mm                                                     Speed: 6.5 m/minute                                                           Board no.                                                                             C.sub.1, mm                                                                           C.sub.2, mm                                                                           C.sub.3, mm                                                                         C.sub.4, mm                                                                         C.sub.av, mm                                                                         σ, mm                        ______________________________________                                        1 -     0.07    0.08    0.07  0.07  0.0725 0.005                              2 -     0.07    0.07    0.07  0.06  0.0675 0.005                              ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Target dimension: 0.07 mm                                                     Speed: 21 m/minute                                                            Board no.                                                                             C.sub.1, mm                                                                           C.sub.2, mm                                                                           C.sub.3, mm                                                                         C.sub.4, mm                                                                         C.sub.av, mm                                                                         σ, mm                        ______________________________________                                        1 -     0.05    0.05    0.06  0.05  0.0525 0.005                              2 -     0.07    0.06    0.07  0.07  0.0675 0.005                              ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Target dimension: 0.10 mm                                                     Speed: 40 m/minute                                                            Board no.                                                                             C.sub.1, mm                                                                           C.sub.2, mm                                                                           C.sub.3, mm                                                                         C.sub.4, mm                                                                         C.sub.av, mm                                                                         σ, mm                        ______________________________________                                        1 -     0.10    0.10    0.08  0.10  0.0950 0.010                              2 -     0.10    0.10    0.10  0.18  0.1050 0.010                              ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        Target dimension: 0.18 mm                                                     Speed: 6.5 m/minute                                                           Board no.                                                                             C.sub.1, mm                                                                           C.sub.2, mm                                                                           C.sub.3, mm                                                                         C.sub.4, mm                                                                         C.sub.av, mm                                                                         σ, mm                        ______________________________________                                        1 -     0.20    0.17    0.19  0.17  0.1875 0.015                              2 -     0.17    0.17    0.17  0.20  0.1775 0.015                              ______________________________________                                    

The results show that a very small chamfer with an extremely smalldeviation in regard of its dimension can be obtained. A standarddeviation of for instance 0.01 mm means that 85% of all chamfers arewithin ±0.01 mm of the target dimension. This is so small a deviationthat it contrary to deviations, such as said ±0.1 mm, obtained usingconventional planing or cutting machines and chamfer dimensions, such assaid 0.3-0.5 mm, not is visual to the eye, not even on large areas suchas floors, walls etc.

EXAMPLE 2

Boards obtained in accordance with Example 1 were joint to larger units,whereby the abrasion in and over the joints were evaluated by thecommonly used Taber Abrasor Method (ISO 4586/2-88). A so called IP value(IP=Initial Point) for the initial abtasion is then obtained. Theevaluation is carried out on the laminate side of the boards and overthe joint between two boards. The difference in level between thevarious boards was in all evaluations measured to be 0.05 mm. Twoevaluations at the chamfer dimensions 0.10 and 0.14 mm were carried outand compared with results obtained with conventionally chamfered boardshaving a chamfer dimension of 0.40 mm. The results are given in Table 5below.

                  TABLE 5                                                         ______________________________________                                                  Evaluation no. 1                                                                           Evaluation no. 2                                                                           Average                                   Chamfer, mm                                                                             IP value     IP value     IP value                                  ______________________________________                                        0.40 (ref.)                                                                             17500        15000        16250                                     0.10      16500        14500        14500                                     0.14      18000        16500        16500                                     ______________________________________                                    

The results show that a reduction as high as 65-75% of the chamferdimension has no or very little influence on the IP value and thus onthe abrasion resistance over the joint. A substantially reduced chamferdimension does thus not imply a reduced abrasion resistance in or overthe chamfer or joint.

EXAMPLE 3

An ultrasonic planing machine having a planing tool made of titanium wascompared with an apparatus in accordance with FIG. 1 and thus usedaccording to the method of the present invention. A thermosettinglaminate of the type disclosed in the European patent 0 329 154 (U.S.Pat. No. 4,940,503) was edge chamfered at an chamfer angle of 45°. Thetitanium tool was worn out, having deep recesses corresponding to thelaminate edge in the tool, after only 6 meters of said edge chamfering.The planing tool used in accordance with the present invention and foredge chamfering of the same laminate, exhibited after 6000 meters ofchamfering no signs of deterioration.

FIG. 1

FIG. 1 schematically shows one embodiment of an apparatus used tocarried out the method of machining, in this case a planing operation,according to the present invention. The apparatus comprises aconventional high-frequency oscillation generator 1, a conventionaldimension adjusting unit 4, a conventional amplitude transforming unit 5and a planing tool 2. The dimension adjusting unit 4 comprises apiezoelectric crystal 8 and the amplitude transforming unit 5 amechanical booster 6 to which a tiller/tool holder 7 in form of amandrel 7' made of titanium is attached. The tool 2, comprises asmachining member, a diamond 3, which is attached to the mandrel 7' byvacuum soldering. The piezoelectric crystal 8 executes when charged withan alternating current a linear vibration, which is propagated throughthe amplitude transforming unit 5 and thus the booster 6 and the mandrel7'. The booster 6, depending on its design, changes generatedhigh-frequency amplitude to a higher or lower level.

An electric alternating current (50 Hz-220 V) is supplied to thehigh-frequency oscillation generator 1 via a connection 10, whereby20,000 Hz is transferred via a connection 11 to the dimension adjustingunit 4 and its piezoelectric crystal 8. A linear vibration is thenpropagated through the amplitude transforming unit 5 and its mechanicalbooster 6 and thus through the mandrel 7' attached thereto. The tool 2and its machining member, the diamond 3, performs a linear vibratingmovement, as indicated by arrow 16, whereby the tool 2 executes saidplaning operation.

FIG. 2

FIG. 2 shows planing i form of edge chamfering of a board 12, suitableused as floor board, consisting of a thermosetting laminate 13 gluedonto a carrier 15 of particle board. The carrier 15 is provided with onegroove 17 and one tenon 18 for joining two or more boards 12 to a largerarea such as a floor surfacing. The thermosetting laminate 13constitutes said board's upper surface and is subjected to edgechamfering by means of the apparatus shown in FIG. 1. The entireapparatus is not depicted, only its tool 2 and its machining member, adiamond 3. The tool 2 also comprises a tool connection 9 by which saidtool 2 is connected to a mandrel 7' (see FIG. 1). The tool 2 performs alinear vibrating movement, as indicated by arrow 16, whereby said tool 2executes said edge chamfering thus providing the thermosetting laminate13 with an edge chamfer 14. The edge chamfering is performed at achamfer angle of 45°.

What is claimed is:
 1. A method for planing a thermosetting laminate, the planing being an edge chamfering of the thermosetting laminate carried out by means of an apparatus comprising at least one high-frequency or ultrasonic oscillation generator and at least one dimension changing or adjusting unit having at least one piezoelectric crystal performing a linear vibration when charged with an alternating current, the linear vibration being propagated through at least one amplitude transforming unit, whereby generated high-frequency or ultrasound is transformed into a linear vibration which during said edge chamfering is propagated via at least one tiller to at least one tool attached to said tiller, said tiller being connected to said amplitude changing unit and said tool comprising at least one diamond, charging the apparatus with electric current; and moving the tool including said diamond into contact with the thermosetting laminate to be edge chamfered, whereby at least said tool performs a linear vibrating movement planing said thermosetting laminate resulting in a chamfer of less than 0.30 mm.
 2. The method according to claim 1, wherein the amplitude transforming unit is a mechanical amplitude transforming unit.
 3. The method according to claim 1, wherein the amplitude transforming unit is an electronic amplitude transforming unit.
 4. The method according to claim 1, wherein the amplitude transforming unit comprises at least one mechanical booster.
 5. The method according to claim 1, wherein the tool holding tiller comprises at least one mandrel.
 6. The method according to claim 1, wherein the high-frequency or ultrasound amplitude has a frequency of 5-60 kHz.
 7. The method according to claim 6, wherein the frequency is 10-40 kHz.
 8. The method according to claim 7, wherein the frequency is 15-25 kHz.
 9. The method according to claim 1, wherein the chamfer is within a range of 0.05-0.20 mm.
 10. The method according to claim 1, wherein the edge chamfering is carried out at a chamfer angle of 10-80°.
 11. The method according to claim 10, wherein the chamfer angle is 30-60°.
 12. The method according to claim 1, wherein the thermosetting laminate comprises at least one material in a form selected from the group consisting of a web, a sheet and cut fibers; the material being impregnated with at least one thermosetting resin which resin is fully cured under heat and pressure.
 13. The method according to claim 12, wherein the material is selected from the group consisting of cellulose, glass fiber and textile.
 14. The method according to claim 12, wherein the thermosetting resin is one selected from the group consisting of a polyester resin, an epoxy resin, a melamine-formaldehyde resin, a urea-formaldehyde resin, a phenol-formaldehyde resin and mixtures thereof.
 15. The method according to claim 12, wherein the thermosetting laminate comprises at least one core consisting of at least one material selected from the group consisting of Kraft paper web and a Kraft paper sheet; said material being impregnated with at least one thermosetting resin.
 16. The method according to claim 15, wherein the thermosetting resin is one selected from the group consisting of an epoxy resin and a phenol-formaldehyde resin.
 17. The method according to claim 12, wherein the thermosetting laminate comprises at least one material selected from the group consisting of a patterned paper web, a monochromatic paper web, a patterned sheet and a monochromatic sheet impregnated with at least one thermosetting resin.
 18. The method according to claim 17, wherein the thermosetting resin is one selected from the group consisting of a urea-formaldehyde resin and a melamine-formaldehyde resin.
 19. The method according to claim 12, wherein the thermosetting laminate comprises at least one overlay, said overlay comprising at least one material selected from the group consisting of a web of α-cellulose fibers and a sheet of α-cellulose fibers; said overlay being impregnated with at least one thermosetting resin.
 20. The method according to claim 19, wherein the thermosetting resin is one selected from the group consisting of a urea-formaldehyde resin and a melamine-formaldehyde resin.
 21. The method according to claim 19, wherein the web or sheet is surfaced with hard particles after which the thermosetting resin is cured.
 22. The method according to claims 21, wherein the hard particles are aluminum oxide particles.
 23. The method according to claim 1, wherein the thermosetting laminate is bonded to a carrier, the carrier being selected from the group consisting of wood, fiber board, particle board and plywood and the thermosetting laminate being subjected to said edge chamfering.
 24. The method according to claim 1, wherein the thermosetting laminate is a floor, wall, ceiling, furniture surfacing or kitchen furnishing, each in a form selected from the group consisting of a form of boards, plates, sheets and panels.
 25. The method according to claim 23, wherein the carrier has at least one groove or tenon.
 26. The method according to claim 24, wherein the carrier has at least one groove or tenon. 